Regulatory Matters (Details) $ / shares in Units, shares in Thousands		3 Months Ended
		Mar. 31, 2021 USD ($) $ / shares	Jun. 30, 2020 shares	Dec. 31, 2020 USD ($)	Sep. 30, 2020 $ / shares
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Preceding period of retained earnings used in calculation of dividend payable		2 years
Retained earnings		$ 1,515,451,000		$ 1,407,723,000
Quarterly common stock dividend (in dollar per share) | $ / shares		$ 0.18			$ 0.16
Preferred Stock, Dividend Rate, Per-Dollar-Amount | $ / shares		$ 16.88
Preferred Stock, Dividend Per Depositary Share		$ 0.422
Depositary Shares | shares			9,000
Issuance of preferred stock, net of issuance costs		217,100,000
Pinnacle Financial
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Cash dividends paid to Pinnacle Financial by Pinnacle Bank		0
Actual
Total capital to risk weighted assets		3,784,041,000		3,678,405,000
Tier I capital to risk weighted assets		2,911,788,000		2,803,541,000
Common Equity Tier I capital to risk weighted assets		2,694,539,000		2,586,292,000
Tier I capital to average assets	[1]	$ 2,911,788,000		$ 2,803,541,000
Actual
Total capital to risk weighted assets (as percent)		0.145		0.143
Tier I capital to risk weighted assets (as percent)		0.112		0.109
Common Equity Tier I capital to risk weighted assets (as percent)		0.103		0.100
Tier I capital to average assets (as percent)	[1]	0.089		0.086
Minimum Capital Requirement
Total capital to risk weighted assets		$ 2,088,413,000		$ 2,063,352,000
Tier I capital to risk weighted assets		1,566,309,000		1,547,514,000
Common Equity Tier I capital		1,174,732,000		1,160,635,000
Tier I capital to average assets	[1]	$ 1,306,257,000		$ 1,298,756,000
Minimum Capital Requirement
Total capital to risk weighted assets (as percent)		0.080		0.080
Tier I capital to risk weighted assets (as percent)		0.060		0.060
Common Equity Tier I capital to risk weighted assets (as percent)		0.045		0.045
Tier I capital to average assets (as percent)	[1]	0.040		0.040
Minimum To Be Well-Capitalized
Total capital to risk weighted assets		$ 2,610,516,000		$ 2,579,190,000
Tier I capital to risk weighted assets		$ 2,088,413,000		$ 2,063,352,000
Minimum To Be Well-Capitalized
Total capital to risk weighted assets (as percent)		0.100		0.100
Tier I capital to risk weighted assets (as percent)		0.080		0.080
Pinnacle Bank
Compliance with Regulatory Capital Requirements under Banking Regulations [Line Items]
Retained earnings		$ 574,300,000
Actual
Total capital to risk weighted assets		3,382,392,000		$ 3,259,538,000
Tier I capital to risk weighted assets		3,059,140,000		2,933,674,000
Common Equity Tier I capital to risk weighted assets		3,059,017,000		2,933,551,000
Tier I capital to average assets	[1]	$ 3,059,140,000		$ 2,933,674,000
Actual
Total capital to risk weighted assets (as percent)		0.130		0.127
Tier I capital to risk weighted assets (as percent)		0.118		0.114
Common Equity Tier I capital to risk weighted assets (as percent)		0.118		0.114
Tier I capital to average assets (as percent)	[1]	0.094		0.091
Minimum Capital Requirement
Total capital to risk weighted assets		$ 2,081,224,000		$ 2,055,892,000
Tier I capital to risk weighted assets		1,560,918,000		1,541,919,000
Common Equity Tier I capital		1,170,688,000		1,156,439,000
Tier I capital to average assets	[1]	$ 1,302,421,000		$ 1,294,033,000
Minimum Capital Requirement
Total capital to risk weighted assets (as percent)		0.080		0.080
Tier I capital to risk weighted assets (as percent)		0.060		0.060
Common Equity Tier I capital to risk weighted assets (as percent)		0.045		0.045
Tier I capital to average assets (as percent)	[1]	0.040		0.040
Minimum To Be Well-Capitalized
Total capital to risk weighted assets		$ 2,601,529,000		$ 2,569,865,000
Tier I capital to risk weighted assets		2,081,224,000		2,055,892,000
Common Equity Tier I capital to risk weighted assets		1,690,994,000		1,670,412,000
Tier I capital to average assets	[1]	$ 1,628,026,000		$ 1,617,541,000
Minimum To Be Well-Capitalized
Total capital to risk weighted assets (as percent)		0.100		0.100
Tier I capital to risk weighted assets (as percent)		0.080		0.080
Common Equity Tier I capital to risk weighted assets (as percent)		0.065		0.065
Tier I capital to average assets (as percent)	[1]	0.050		0.050

[1] (*) Average assets for the above calculations were based on the most recent quarter.